Defense Secretary Ashton Carter warned Americans to expect more raids on Islamic State strongholds, while maintaining there will be no combat missions for US troops on the ground after a member of the Special Forces died in a hostage rescue operation.

"When we find opportunities to do things that will effectively prosecute the campaign, we're going to do that," Carter said at Friday’s Pentagon briefing. "Raids is one of those categories and I suspect that we'll have further opportunities in the future and we're going to avail ourselves."

Master Sergeant Joshua Wheeler, a 39-year-old veteran of 14 official combat deployments, died of gunshot wounds sustained during a raid on an Islamic State (IS, formerly known as ISIS/ISIL) compound on Wednesday night, which was led by Iraqi Kurdish forces.

The Peshmerga troops and US Special Forces mounted the rescue operation in the area of Hawija, an IS stronghold west of Kirkuk. About 70 captives were successfully freed after US troops were dropped in by helicopter, while Kurdish fighters attacked by land, with the goal of freeing the Kurdish, Sunni and other fighters captured by IS militants.

Wheeler and the other Special Forces members were participating solely in an “advise-and-assist” role during the raid, Carter told reporters Friday, insisting that his death in a gunfight does not change the role of the US troops in Iraq.

The defense secretary said he made the call to conduct the raid when intelligence showed "a mass execution was imminent."

"They expected to be executed that day after morning prayers," Carter said, noting that a large hole was dug near the compound for their bodies.

"As the compound was being stormed, the plan was not for the US advise-and-assist and accompanying forces to enter the compound or be involved in the firefight," Carter said.

"However, when a firefight ensued, this American did what I'm very proud Americans do in that situation, he ran to the sound of gunfire," and helped protect the Iraqi forces who were breaching the wall.

More than 20 of the freed captives were members of the Iraqi security forces, while a number of IS militants were killed and five were captured in the raid, the Pentagon said on Thursday. Kurdish officials said that at least 20 jihadists died during the operation, while the US put the number closer to 10.

Wheeler, a decorated veteran commando with 14 deployments in Iraq and Afghanistan over more than 20 years of service, is the first American combat casualty in the fight against IS and the first in Iraq since November 2011. His body will be returned to the US on Saturday in a ceremony that will be attended by his family, as well as by Carter and his wife.

In June, President Barack Obama authorized an additional 450 US troops be deployed in Iraq, bringing the total number of US military personnel there to about 3,500. The majority are in training and advising roles.